Perception du risque ailleurs : Aux Etat-Unis, cet article du NYT sur l’épidémie de grippe

How bad is this flu season? At the moment, the 2017-2018 flu season is considered “moderately severe.” Large numbers of Americans have fallen ill, and every state except Hawaii has reported widespread flu activity. But some regions have been hit harder than others. More important, the number of people hospitalized or dying from flu nationwide is not unusually high. This season is closely paralleling the 2014-2015 season, which was dominated by the same H3N2 flu strain and was also “moderately severe.”

Is this year’s flu strain unusually dangerous? H3N2 is the most dangerous of the four seasonal flu strains, but it is not new nor uniquely lethal. A typical season mixes two Type A strains — H1N1 and H3N2, and two Type B strains — Victoria and Yamagata. (The B strains normally arrive later and are rarer.) As of Jan. 7, about 78 percent of all samples genetically sequenced have been H3N2, according to the Centers for Disease Control and Prevention. That strain first emerged in Hong Kong in 1968 and killed an estimated 1 million people around the world that year. But it has circulated ever since, constantly undergoing small mutations. Many people have had it, and an H3N2 strain is a component of every season’s flu shot, so partial immunity is widespread. La suite